The primay objective of this program is to obtain a better understanding of aging. It will focus on studies of human tissue obtained from autopsy, surgical pathology, and clinical pathology laboratories. Cells will be taken from tissues of young and old populations and comparative morphological, biochemical, and physiological studies performed. The projects presented include: 1) A study of non-disjunction in the human oocyte: 2) A study of karyotypes including the X chromosome in the aged population; 3) Investigation of a senescent gene(s) in aged fiborblasts; 4) The potential for regeneration and in aged muscle tissue; 5) Changes in membrane antigens in lymphocytes of aged populations; 6) Changes in primary and secondary lymphoid populations in aging; 7) The possible correlation of specific HLA markers in Alzheimer's disease; 8) The significance of polyamines in membrane structure in aged red blood cells; 9) Alterations in endothelial cell structure and function with aging; 10) Changes in hormone receptors in cells of the female reproductive tract with aging; 11) Changes in enzyme activity in the brain of aged populations; 12) Changes in retinal pigment cells with aging; 13) Changes in components of the intervertebral disc with aging; 14) Investigations in hyaluronic acid composition of the eye and joints with aging; 15) Studies of the composition of cerebral spinal fluid and intraocular fluid with aging.